1. Technical Field
The present disclosure relates to a centrifugal fan.
2. Description of Related Art
Electric apparatuses, such as notebook computers, generate heat when operating. If the heat is not dissipated efficiently, the electric apparatuses may malfunction. In serious situations, the heat may damage electric elements in the electric apparatuses. Furthermore, burning electric elements may hurt users. One method for reducing the heat in electric apparatuses involves the use of centrifugal fans therein. Each centrifugal fan may include blades and a driving device. Heat generated by operation of the electric elements may be dissipated by airflow generated by the centrifugal fans.
In recent years, due to the increased efficiency and increased working temperature of electronic chips, the driving devices of centrifugal fans need to have increased rotating speed to enhance airflow. However, with increased rotating speed, the centrifugal fans may generate increased noise, which may disturb users.
FIG. 1 is a top view of a conventional centrifugal fan 100. As show in FIG. 1, the conventional centrifugal fan 100 includes a housing 110, a driving device 130, and blades 120. The housing 100 includes a base 112 and struts 114. Because each of the struts 114 connected between the base 112 and the remainder of the housing 110 are not designed in any particular manner, the peripheral edges of each of the struts 114 are formed as two substantially parallel straight lines. When the driving device 130 rotates the blades 120 in a direction 140, air is drawn into hollow regions 116 located between the struts 114 and exhausted from an air outlet 118 of the housing 110. At this time, some of the air collides with the struts 114 and generates loud narrowband noise.
Some manufacturers may use materials to decrease the noise generated by the conventional centrifugal fan. For example, some manufacturers may increase the thickness of an external case of an electric apparatus that includes the conventional centrifugal fan in the external case. Moreover, sound-insulation boards or sound-absorbent cotton may be placed adjacent to the conventional centrifugal fan. Consequently, the material cost of the electric apparatus may increase, and the amount of space in the electric apparatus may be decreased due to the addition of such sound-insulation boards or sound-absorbent cotton, possibly making necessary changes to the positions where elements may be located in the external case. Furthermore, there are several types of blades in use in present-day centrifugal fans. When manufacturers use a housing to accommodate different types of blades, even though this allows different types of blades to be fitted for the same housing, the level of noise is still difficult to control due to the straight formation of the peripheral edges of the struts in the conventional centrifugal fan.